1semaphore.h(0P)            POSIX Programmer's Manual           semaphore.h(0P)
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PROLOG

6       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
7       implementation of this interface may differ (consult the  corresponding
8       Linux  manual page for details of Linux behavior), or the interface may
9       not be implemented on Linux.
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NAME

12       semaphore.h — semaphores
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SYNOPSIS

15       #include <semaphore.h>
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DESCRIPTION

18       The <semaphore.h> header shall define the sem_t type, used in  perform‐
19       ing semaphore operations. The semaphore may be implemented using a file
20       descriptor, in which case applications are able to open up at  least  a
21       total of {OPEN_MAX} files and semaphores.
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23       The  <semaphore.h> header shall define the symbolic constant SEM_FAILED
24       which shall have type sem_t *.
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26       The following shall be declared as functions and may also be defined as
27       macros. Function prototypes shall be provided.
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30           int    sem_close(sem_t *);
31           int    sem_destroy(sem_t *);
32           int    sem_getvalue(sem_t *restrict, int *restrict);
33           int    sem_init(sem_t *, int, unsigned);
34           sem_t *sem_open(const char *, int, ...);
35           int    sem_post(sem_t *);
36           int    sem_timedwait(sem_t *restrict, const struct timespec *restrict);
37           int    sem_trywait(sem_t *);
38           int    sem_unlink(const char *);
39           int    sem_wait(sem_t *);
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41       Inclusion  of the <semaphore.h> header may make visible symbols defined
42       in the <fcntl.h> and <time.h> headers.
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44       The following sections are informative.
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APPLICATION USAGE

47       None.
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RATIONALE

50       None.
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FUTURE DIRECTIONS

53       None.
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SEE ALSO

56       <fcntl.h>, <sys_types.h>, <time.h>
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58       The   System   Interfaces   volume   of   POSIX.1‐2017,    sem_close(),
59       sem_destroy(),   sem_getvalue(),  sem_init(),  sem_open(),  sem_post(),
60       sem_timedwait(), sem_trywait(), sem_unlink()
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63       Portions of this text are reprinted and reproduced in  electronic  form
64       from  IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
65       table Operating System Interface (POSIX), The Open Group Base  Specifi‐
66       cations  Issue  7, 2018 Edition, Copyright (C) 2018 by the Institute of
67       Electrical and Electronics Engineers, Inc and The Open Group.   In  the
68       event of any discrepancy between this version and the original IEEE and
69       The Open Group Standard, the original IEEE and The Open Group  Standard
70       is  the  referee document. The original Standard can be obtained online
71       at http://www.opengroup.org/unix/online.html .
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73       Any typographical or formatting errors that appear  in  this  page  are
74       most likely to have been introduced during the conversion of the source
75       files to man page format. To report such errors,  see  https://www.ker‐
76       nel.org/doc/man-pages/reporting_bugs.html .
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80IEEE/The Open Group                  2017                      semaphore.h(0P)
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